Post some examples so I can compare, in my head Mark and Cobain vocally sound very different to me.
He sounds kinda like him when he shouts the chorus, but the rest of the song I don't really hear it. His style is just a lot more melancholic and a lot less energetic and upbeat to my ears.
Mudhoney always were way more garage punk than the other classic grunge bands, like Melvins they don't really even fit in with that whole scene imo.